Cycloolefins can be polymerized through the olefin structure to yield polycycloaliphatics, or through a ring-opening process to yield unsaturated linear polymers. The latter process has particular appeal since the resulting polymers are sulfur-vulcanizable. Cyclopentene is a readily available ethylene production by-product, and considerable art has focused on the ring-opening polymerization and copolymerization of cyclopentene. Dicyclopentadiene is another readily available ethylene production by-product, but not as much consideration has been given in the prior art to dicyclopentadiene polymers. Recent U.S. Patents directed to cyclopentene and dicyclopentadiene polymers include U.S. Pat. Nos. 3,778,420, 3,781,257, 3,790,545, 3,853,830, and 4,002,815.
Norbornene (bicyclo[2.2.1]-hept-2-ene) and substituted norbornenes can be produced by Diels-Alder reaction of cyclopentadiene with selected olefins. U.S. Pat. No. 3,074,918 is directed to polymerization of cyclic olefins having at least one unsubstituted ring double bond and not more than one double bond in each ring, such as dicyclopentadiene, 1,2-dihydrodicyclopentadiene, norbornene, or substituted norbornenes. U.S. Pat. No. 3,546,183 describes elastomer polymers or polymers which can be used as bases for elastomer compositions, having in their structural formula units of alkyl-5-bicyclo[2.2.1]hept-2-ene or alkoxy-5-bicyclo[2.2.1]hept-2-ene. Other U.S. patents directed to norbornene and substituted norbornene polymers include U.S. Pat. Nos. 2,721,189, 2,831,037, 2,932,630, 3,330,815, 3,367,924, 3,467,633, 3,836,593, 3,879,343 and 4,020,021.
Tetracyclododecene (1,4:5,8-dimethano-1,2,3,4,4a,5,8,8a-octahydronaphthalene) and alkyltetracyclododecenes can be made by Diels-Alder reaction of cyclopentadiene with norbornene or substituted norbornenes. U.S. Pat. No. 3,557,072 describes plastomers obtained by polymerizing tetracyclododecene and its alkyl derivatives with 0 to 99% of a copolymerizable compound, for example, an ethylenically-unsaturated compound such as norbornene and its alkyl derivatives, styrene, and the cyclic olefins.
Acyclic olefins are commonly used as molecular weight modifiers in cycloolefin polymerizations. See, for example, U.S. Pat. Nos. 4,002,815, 4,025,708, 4,069,376 and 4,110,528.
Polymers of dicyclopentadiene, alone or with acyclic monoolefins or nonconjugated acyclic olefins, have excellent glass transition temperatures but are difficult to process. Polymers of tetracyclododecene or substituted tetracyclododecenes, alone or with acyclic monoolefins or nonconjugated acyclic olefins, generally have even higher glass transition temperatures as well as improved stability but are still more difficult to process. Finally, polymers of norbornene or most alkylnorbornenes with acyclic monoolefins or nonconjugated acyclic olefins process easily but have lower glass transition temperatures than desired for some applications. Use of dimethylnorbornene or isopropyl-norbornene provides higher glass transition temperature properties than most other alkylnorbornenes, but still less than desired for some applications.
New copolymers are desired having a balance of satisfactory processability, stability and glass transition temperatures, as well as a balance of other properties normally associated with thermoformable polymers.